(1) Field of the Invention
The present invention pertains to a safety valve designed to automatically interrupt or stop a flow of fluid through the valve in response to the valve being subjected to a predetermined minimum impact force or vibration, and in response to the valve being subjected to heat above a predetermined minimum temperature.
(2) Description of the Related Art
The prior art includes various different types of valves that are designed to interrupt or stop a flow of fluid in response to being subjected to some external condition. An example of such a prior art valve is disclosed in the Prater U.S. Pat. No. 2,804,317, which discloses a valve constructed to automatically interrupt fluid flow through the valve in response to the valve exterior housing being subjected to an excessive impact force or excessive vibration sufficient to fracture the valve housing. Valves of this type are frequently employed on storage tanks containing a pressurized fluid such as propane, butane, or the like. The valve is positioned between the storage tank and a conduit or some other carrier of the flow of fluid from the tank. The valve includes means that are automatically actuated upon the severing of a portion of the valve housing to stop the flow of fluid from the tank. The Newman et al. U.S. Pat. No. 2,586,248; Hicks U.S. Pat. No. 4,488,566; Sturgis et al. U.S. Pat. No. 4,727,903; Jindra et al. U.S. Pat. No. 4,792,115; Friend et al. U.S. Pat. No. 4,887,631; Silagy U.S. Pat. No. 4,932,431; Sturgis U.S. Pat. No. 4,974,623; and Silagy U.S. Pat. No. 5,027,845 all disclose valves constructed to automatically interrupt fluid flow in response to being subjected to a minimum temperature level. Valves of this type are typically employed between storage tanks of combustible fluids and the supply line of the fluid leading from the tank. These valves operate to automatically close when the exteriors of the valves are subjected to a predetermined minimum temperature, thereby preventing the combustible fluid from escaping from the tank uncontrollably should the fuel line leading from the tank be broken due to a fire.
A more specialized safety valve construction performs the function of automatically interrupting fluid flow through the valve when the valve is subjected to an external impact force and/or when the valve is subjected to an external temperature exceeding a predetermined minimum temperature. Examples of dual function valves of this type are disclosed in the Johnsen U.S. Pat. No. 2,048,388 and Ely U.S. Pat. No. 4,745,940. Valves of this type are frequently employed on service station gasoline pumps and on gas or fuel lines leading into buildings.
Despite the ability of the specialized dual function safety valves to interrupt fluid flow when subjected to an excessive impact force or vibration or excessive heat, many of the dual function valves have not found widespread application due to their complicated and intricate constructions. Many prior art dual function valves have elaborate constructions that are expensive to manufacture, with some valves having such intricate constructions that they can only be manufactured by hand.
It is therefore an object of the present invention to provide a novel, more simplified construction for a dual function safety valve which automatically interrupts fluid flow through the valve in response to the valve being subjected to a minimum external impact force or vibration and/or in response to the valve being subjected to an external temperature that exceeds a predetermined minimum temperature. The more simplified construction of the valve of the present invention enables it to be more easily, and more economically manufactured. Although the safety valve of the invention has a more simplified and less intricate construction than dual function valves of the prior art, the design of the valve ensures its reliable operation in automatically interrupting fluid flow through the valve when subjected to a minimum impact force or vibration and/or excessive heat.